To characterize the relationship between chlorhexidine gluconate (CHG) skin concentration and skin microbial colonization.

Serial cross-sectional study.

Adult patients in medical intensive care units (ICUs) from 7 hospitals; from 1 hospital, additional patients colonized with carbapenemase-producing Enterobacterales (CPE) from both ICU and non-ICU settings. All hospitals performed routine CHG bathing in the ICU.

Skin swab samples were collected from adjacent areas of the neck, axilla, and inguinal region for microbial culture and CHG skin concentration measurement using a semiquantitative colorimetric assay. We used linear mixed effects multilevel models to analyze the relationship between CHG concentration and microbial detection. We explored threshold effects using additional models.

We collected samples from 736 of 759 (97%) eligible ICU patients and 68 patients colonized with CPE. On skin, gram-positive bacteria were cultured most frequently (93% of patients), followed by Candida species (26%) and gram-negative bacteria (20%). The adjusted odds of microbial recovery for every twofold increase in CHG skin concentration were 0.84 (95% CI, 0.80–0.87; P < .001) for gram-positive bacteria, 0.93 (95% CI, 0.89–0.98; P = .008) for Candida species, 0.96 (95% CI, 0.91–1.02; P = .17) for gram-negative bacteria, and 0.94 (95% CI, 0.84–1.06; P = .33) for CPE. A threshold CHG skin concentration for reduced microbial detection was not observed.

On a cross-sectional basis, higher CHG skin concentrations were associated with less detection of gram-positive bacteria and Candida species on the skin, but not gram-negative bacteria, including CPE. For infection prevention, targeting higher CHG skin concentrations may improve control of certain pathogens.

To assess whether measurement and feedback of chlorhexidine gluconate (CHG) skin concentrations can improve CHG bathing practice across multiple intensive care units (ICUs).

A before-and-after quality improvement study measuring patient CHG skin concentrations during 6 point-prevalence surveys (3 surveys each during baseline and intervention periods).

The study was conducted across 7 geographically diverse ICUs with routine CHG bathing.

Adult patients in the medical ICU.

CHG skin concentrations were measured at the neck, axilla, and inguinal region using a semiquantitative colorimetric assay. Aggregate unit-level CHG skin concentration measurements from the baseline period and each intervention period survey were reported back to ICU leadership, which then used routine education and quality improvement activities to improve CHG bathing practice. We used multilevel linear models to assess the impact of intervention on CHG skin concentrations.

We enrolled 681 (93%) of 736 eligible patients; 92% received a CHG bath prior to survey. At baseline, CHG skin concentrations were lowest on the neck, compared to axillary or inguinal regions (P < .001). CHG was not detected on 33% of necks, 19% of axillae, and 18% of inguinal regions (P < .001 for differences in body sites). During the intervention period, ICUs that used CHG-impregnated cloths had a 3-fold increase in patient CHG skin concentrations as compared to baseline (P < .001).

Routine CHG bathing performance in the ICU varied across multiple hospitals. Measurement and feedback of CHG skin concentrations can be an important tool to improve CHG bathing practice.

Cohorting patients who are colonized or infected with multidrug-resistant organisms (MDROs) protects uncolonized patients from acquiring MDROs in healthcare settings. The potential for cross transmission within the cohort and the possibility of colonized patients acquiring secondary isolates with additional antibiotic resistance traits is often neglected. We searched for evidence of cross transmission of KPC+ Klebsiella pneumoniae (KPC-Kp) colonization among cohorted patients in a long-term acute-care hospital (LTACH), and we evaluated the impact of secondary acquisitions on resistance potential.

Genomic epidemiological investigation.

A high-prevalence LTACH during a bundled intervention that included cohorting KPC-Kp–positive patients.

Whole-genome sequencing (WGS) and location data were analyzed to identify potential cases of cross transmission between cohorted patients.

Secondary KPC-Kp isolates from 19 of 28 admission-positive patients were more closely related to another patient’s isolate than to their own admission isolate. Of these 19 cases, 14 showed strong genomic evidence for cross transmission (<10 single nucleotide variants or SNVs), and most of these patients occupied shared cohort floors (12 patients) or rooms (4 patients) at the same time. Of the 14 patients with strong genomic evidence of acquisition, 12 acquired antibiotic resistance genes not found in their primary isolates.

Acquisition of secondary KPC-Kp isolates carrying distinct antibiotic resistance genes was detected in nearly half of cohorted patients. These results highlight the importance of healthcare provider adherence to infection prevention protocols within cohort locations, and they indicate the need for future studies to assess whether multiple-strain acquisition increases risk of adverse patient outcomes.

We assessed the impact of personal protective equipment (PPE) doffing errors on healthcare worker (HCW) contamination with multidrug-resistant organisms (MDROs).

Prospective, observational study.

The study was conducted at 4 adult ICUs at 1 tertiary-care teaching hospital.

HCWs who cared for patients on contact precautions for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci, or multidrug-resistant gram-negative bacilli were enrolled. Samples were collected from standardized areas of patient body, garb sites, and high-touch environmental surfaces in patient rooms. HCW hands, gloves, PPE, and equipment were sampled before and after patient interaction. Research personnel observed PPE doffing and coded errors based on CDC guidelines.

We enrolled 125 HCWs; most were nurses (66.4%) or physicians (19.2%). During the study, 95 patients were on contact precautions for MRSA. Among 5,093 cultured sites (HCW, patient, environment), 652 (14.7%) yielded the target MDRO. Moreover, 45 HCWs (36%) were contaminated with the target MDRO after patient interactions, including 4 (3.2%) on hands and 38 (30.4%) on PPE. Overall, 49 HCWs (39.2%) made multiple doffing errors and were more likely to have contaminated clothes following a patient interaction (risk ratio [RR], 4.69; P = .04). All 4 HCWs with hand contamination made doffing errors. The risk of hand contamination was higher when gloves were removed before gowns during PPE doffing (RR, 11.76; P = .025).

When caring for patients on CP for MDROs, HCWs appear to have differential risk for hand contamination based on their method of doffing PPE. An intervention as simple as reinforcing the preferred order of doffing may reduce HCW contamination with MDROs.

Bathing intensive care unit (ICU) patients with 2% chlorhexidine gluconate (CHG)–impregnated cloths decreases the risk of healthcare-associated bacteremia and multidrug-resistant organism transmission. Hospitals employ different methods of CHG bathing, and few studies have evaluated whether those methods yield comparable results.

To determine whether 3 different CHG skin cleansing methods yield similar residual CHG concentrations and bacterial densities on skin.

Prospective, randomized 2-center study with blinded assessment.

Healthcare personnel in surgical ICUs at 2 tertiary-care teaching hospitals in Chicago, Illinois, and Boston, Massachusetts, from July 2015 to January 2016.

Cleansing skin of one forearm with no-rinse 2% CHG-impregnated polyester cloth (method A) versus 4% CHG liquid cleansing with rinsing on the contralateral arm, applied with either non–antiseptic-impregnated cellulose/polyester cloth (method B) or cotton washcloth dampened with sterile water (method C).

In total, 63 participants (126 forearms) received method A on 1 forearm (n=63). On the contralateral forearm, 33 participants received method B and 30 participants received method C. Immediately and 6 hours after cleansing, method A yielded the highest residual CHG concentrations (2500 µg/mL and 1250 µg/mL, respectively) and lowest bacterial densities compared to methods B or C (P<.001).

In healthy volunteers, cleansing with 2% CHG-impregnated cloths yielded higher residual CHG concentrations and lower bacterial densities than cleansing with 4% CHG liquid applied with either of 2 different cloth types and followed by rinsing. The relevance of these differences to clinical outcomes remains to be determined.

Infect Control Hosp Epidemiol 2018;39:405–411

To identify modifiable risk factors for acquisition of Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae (KPC) colonization among long-term acute-care hospital (LTACH) patients.

Multicenter, matched case-control study.

Four LTACHs in Chicago, Illinois.

Each case patient included in this study had a KPC-negative rectal surveillance culture on admission followed by a KPC-positive surveillance culture later in the hospital stay. Each matched control patient had a KPC-negative rectal surveillance culture on admission and no KPC isolated during the hospital stay.

From June 2012 to June 2013, 2,575 patients were admitted to 4 LTACHs; 217 of 2,144 KPC-negative patients (10.1%) acquired KPC. In total, 100 of these patients were selected at random and matched to 100 controls by LTACH facility, admission date, and censored length of stay. Acquisitions occurred a median of 16.5 days after admission. On multivariate analysis, we found that exposure to higher colonization pressure (OR, 1.02; 95% CI, 1.01–1.04; P=.002), exposure to a carbapenem (OR, 2.25; 95% CI, 1.06–4.77; P=.04), and higher Charlson comorbidity index (OR, 1.14; 95% CI, 1.01–1.29; P=.04) were independent risk factors for KPC acquisition; the odds of KPC acquisition increased by 2% for each 1% increase in colonization pressure.

Higher colonization pressure, exposure to carbapenems, and a higher Charlson comorbidity index independently increased the odds of KPC acquisition among LTACH patients. Reducing colonization pressure (through separation of KPC-positive patients from KPC-negative patients using strict cohorts or private rooms) and reducing carbapenem exposure may prevent KPC cross transmission in this high-risk patient population.

Infect Control Hosp Epidemiol 2017;38:670–677

Prevalence of blaKPC-encoding Enterobacteriaceae (KPC) in Chicago long-term acute care hospitals (LTACHs) rose rapidly after the first recognition in 2007. We studied the epidemiology and transmission capacity of KPC in LTACHs and the effect of patient cohorting.

Data were available from 4 Chicago LTACHs from June 2012 to June 2013 during a period of bundled interventions. These consisted of screening for KPC rectal carriage, daily chlorhexidine bathing, medical staff education, and 3 cohort strategies: a pure cohort (all KPC-positive patients on 1 floor), single rooms for KPC-positive patients, and a mixed cohort (all KPC-positive patients on 1 floor, supplemented with KPC-negative patients). A data-augmented Markov chain Monte Carlo (MCMC) method was used to model the transmission process.

Average prevalence of KPC colonization was 29.3%. On admission, 18% of patients were colonized; the sensitivity of the screening process was 81%. The per admission reproduction number was 0.40. The number of acquisitions per 1,000 patient days was lowest in LTACHs with a pure cohort ward or single rooms for colonized patients compared with mixed-cohort wards, but 95% credible intervals overlapped.

Prevalence of KPC in LTACHs is high, primarily due to high admission prevalence and the resultant impact of high colonization pressure on cross transmission. In this setting, with an intervention in place, patient-to-patient transmission is insufficient to maintain endemicity. Inclusion of a pure cohort or single rooms for KPC-positive patients in an intervention bundle seemed to limit transmission compared to use of a mixed cohort.

Infect Control Hosp Epidemiol 2015;36(10):1148–1154

To determine anatomic sites of colonization in patients and to assess environmental contamination with Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae.

We conducted a cross-sectional microbiologic survey of 33 patients and their environments at 6 long-term acute care hospitals (LTACHs) in metropolitan Chicago. Swab samples of anatomic sites and inanimate surfaces in patients' rooms and common areas were cultured. blaKPC was verified by polymerase chain reaction. Patient charts were reviewed for covariates known to be associated with colonization and environmental contamination.

Mean age was 66 years. Median length of stay prior to surveillance was 50 days. Thirty (91%) patients were mechanically ventilated, 32 (97%) were bedbound, and 27 (82%) had fecal incontinence. Of the 24 patients with KPC-producing Enterobacteriaceae recovered from 1 or more anatomic sites, 23 (96%) had KPC-producing Enterobacteriaceae detected at 1 or more skin sites. Skin colonization was more common in patients with positive rectal/stool swab cultures or positive clinical cultures (P <.001). Rectal/stool swab was the single most sensitive specimen for detecting KPC-producing Enterobacteriaceae colonization (sensitivity, 88%; 95% confidence interval [CI], 68%-97%); addition of inguinal skin swab culture resulted in detection of all colonized patients (sensitivity, 100%; 95% CI, 86%-100%). Only 2 (0.5%) of 371 environmental specimens grew KPC-producing Enterobacteriaceae.

Culture of more than 1 anatomic site was required to detect all KPC-producing Enterobacteriaceae-colonized Patients. Skin colonization was common, but environmental contamination was rare. These results can guide development of multimodal interventions for control of KPC-producing Enterobacteriaceae in LTACHs.

To determine whether transfer from a long-term care facility (LTCF) is a risk factor for colonization with Klebsiella pneumoniae carbapenemase (KPC)–producing Enterobacteriaceae upon acute care hospital admission.

Microbiologic survey and nested case-control study.

Four hospitals in a metropolitan area (Chicago) with an early KPC epidemic.

Hospitalized adults.

Patients transferred from LTCFs were matched 1 : 1 to patients admitted from the community by age (± 10 years), admitting clinical service, and admission date (± 2 weeks). Rectal swab specimens were collected within 3 days after admission and tested for KPC-producing Enterobacteriaceae. Demographic and clinical information was extracted from medical records.

One hundred eighty patients from LTCFs were matched to 180 community patients. KPC-producing Enterobacteriaceae colonization was detected in 15 (8.3%) of the LTCF patients and 0 (0%) of the community patients (P<.001). Prevalence of carriage differed by LTCF subtype: 2 of 135 (1.5%) patients from skilled nursing facilities without ventilator care (SNFs) were colonized upon admission, compared to 9 of 33 (27.3%) patients from skilled nursing facilities with ventilator care (VSNFs) and 4 of 12 (33.3%) patients from long-term acute care hospitals (LTACHs; P<.001). In a multivariable logistic regression model adjusted for a propensity score that predicted LTCF subtype, patients admitted from VSNFs or LTACHs had 7.0-fold greater odds of colonization (ie, odds ratio; 95% confidence interval, 1.3–42; P = .022) with KPC-producing Enterobacteriaceae than patients from an SNF.

Patients admitted to acute care hospitals from high-acuity LTCFs (ie, VSNFs and LTACHs) were more likely to be colonized with KPC-producing Enterobacteriaceae than were patients admitted from the community. Identification of healthcare facilities with a high prevalence of colonized patients presents an opportunity for focused interventions that may aid regional control efforts.

To determine the effect of a bundle of infection control interventions on the horizontal transmission of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae during an outbreak.

Quasi-experimental study.

Long-term acute care hospital.

On July 23,2008, a bundled intervention was implemented: daily 2% Chlorhexidine gluconate baths for patients, enhanced environmental cleaning, surveillance cultures at admission, serial point prevalence surveillance (PPS), isolation precautions, and training of personnel. Baseline PPS was performed before the intervention was implemented. Any gram-negative rod isolate suspected of KPC production underwent a modified Hodge test and, if results were positive, confirmatory polymerase chain reaction testing. Clinical cases were defined to occur for patients whose samples yielded KPC-positive gram-negative rods in clinical cultures.

Baseline PPS performed on June 17, 2008, showed a prevalence of colonization with KPC-producing isolates of 21% (8 of 39 patients screened). After implementation of the intervention, monthly PPS was performed 5 times, which showed prevalences of colonization with KPC-producing isolates of 12%, 5%, 3%, 0%, and 0% (P < .001). From January 1, 2008, until the intervention, 8 KPC-positive clinical cases—suspected to be due to horizontal transmission—were detected. From implementation of the intervention through December 31, 2008, only 2 KPC-positive clinical cases, both in August 2008, were detected. From January 1 through December 31, 2008, 8 patients were detected as carriers of KPC-producing isolates at admission to the institution, 4 patients before and 4 patients after the intervention.

A bundled intervention was successful in preventing horizontal spread of KPC-producing gram-negative rods in a long-term acute care hospital, despite ongoing admission of patients colonized with KPC producers.